''Cross-Section of The World's Most Prosperous Department Store," had a minimum bid of $20,000 and was offered by Nate D. Sanders. Yet it is noteworthy mainly because of the racial epithet that appears on the illustration.

For those unfamiliar with Dr. Seuss' early works, which sometimes featured political and racist content, "Cross-Section" can be shocking. Seuss was a liberal Democrat revered for his childhood works like "How the Grinch Stole Christmas!" and "The Cat in the Hat," but his early workoften painted blacks and other ethnic groups in unflattering and outright racist terms.

In the "Cross-Section" painting, a group of men can be seen shopping in a department store for objects that can make their lives difficult. The last image shows several African Americans in black face and disproportionate red lips, and displays the N-word prominently.

The ''Cross-Section of The World's Most Prosperous Department Store," is now on sale for $20,000 on the website of Nate D. Sanders, the memorabilia dealer that tried to auction the Seuss work. The drawing previously belonged to a private collector, the firm told CNBC.

"It just needs the right buyer," said Nate D. Sanders' P.R. director, Sam Heller. "There is definitely a market for that."

The Seuss few people talk about

Yet Charles Cohen, a dentist and author of "The Seuss, The Whole Seuss and Nothing but the Seuss," told CNBC that other ethnic and social groups were a target of Seuss' sometimes poisonous pen.

Seuss responded with jokes about Africans-Americans when they were the subject of various entertainment media, Cohen said, adding that Seuss' 1929 drawing wouldn't come as a surprise to more inquisitive fans of Dr. Seuss.

Seuss "did not single out African-Americans for ridicule," said Cohen. "He drew weekly cartoons and he, like his fellow cartoonists, made fun of everyone: women, Jews, Arabs, Scots, Englishmen, Welshmen, black Americans and Africans, Asians, etc."

During World War II, Seuss portrayed several stereotypical and racist cartoons of Japanese people, showing them with buck teeth, small eyes and a pig-nose. He eventually moved away from offensive drawings, which his defenders insist shouldn't diminish the books and art millions have come to revere in their childhood.

"Ted changed the face of reading in America," said Cohen. "So many children had learned how to read through the series of Dick and Jane primers, which featured illustrations of treacly children and their dog Spot, with stultifying text like "Look, Dick, look. See Spot run. Run, Spot, run."

Cohen added: "Equally important, but less well known, is the fact that Ted specifically created stories to help children read at a younger age than was thought possible back in the 1950s."

Later in his career, Dr. Seuss changed some of his opinions. His book "Horton Hears a Who!" —published in the 1950s—was perceived for many as an apology to the Japanese people. The book was dedicated to Seuss' friend, Mitsugi Nakamura.

In addition, when working for the left-wing publication PM during World War II, Dr. Seuss may have been forced to re-evaluate his beliefs, said Cohen. He added that being exposed to liberal ideas led Seuss to question the treatment of minorities in the U.S., especially when there were fights abroad to protect Jews.

"Ted definitely did draw cartoons that depicted ethnic, religious, and gender stereotypes that were commonly held at the time," said Cohen. "But he became the man who championed equality and taught tolerance to generations of young readers."

Dr. Seuss is not the only famous cartoonist with controversial works. Hergé, the father of "The Adventures of Tintin" has been accused of paternalism and racism when it comes to the representation of Congolese people in "Tintin in Congo."

The French magazine L'Express reported that a complaint was filed against "Tintin in Congo" in Belgium in 2007. The plaintiff, who is originally from Congo, wanted the cartoon to be banned due to his belief that the content was racist and xenophobic.